market-sizing-analysis Skill (wshobson) for Claude: TAM, SAM, SOM

Makes Claude size a market with TAM, SAM and SOM using top-down, bottom-up and value-theory methods.

Installs: 12K; on skills.sh
Stars: 42.1K; on GitHub
Files: 3; besides SKILL.md
Updated: Oct 2026; last repo commit

market-sizing-analysis makes Claude calculate three numbers for a startup idea: TAM (total addressable market), SAM (the part you can serve) and SOM (what you can realistically win in 3 to 5 years). It uses three methods: top-down from industry reports, bottom-up from customer segments and pricing, and value theory from willingness to pay.

The reference file walks through six steps, from defining the market to triangulating the result, with notes for SaaS, marketplace, consumer and B2B services markets and common mistakes. A data-sources guide lists where to find figures, and a worked SaaS example sizes an AI email marketing product. The skill bundles no scripts. Claude does the arithmetic from figures you supply or find, so check the sources it cites.

Good for

Founders sizing the market for a pitch or business plan
Analysts validating the market opportunity for a new venture
Product teams estimating addressable revenue for a new product

Install market-sizing-analysis

Claude Code

Copy this prompt.

Install the market-sizing-analysis skill in Claude Code. Run this command:

/plugin marketplace add wshobson/agents
/plugin install startup-business-analyst@claude-code-workflows

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

The plugin adds 5 skills, 1 agent (startup-analyst) and 3 commands (business-case, financial-projections, market-opportunity), counted from the repo. Its marketplace entry lists no hooks or MCP servers. The skills CLI command installs only this skill, without the plugin's agents or commands (the README says so).

Built from the package data we hold. Not yet tested by us. Source.

What's in the skill

When it loads

Calculate TAM/SAM/SOM for market opportunities using top-down, bottom-up, and value theory methodologies. Use this skill when sizing markets, estimating addressable revenue, validating market opportunity for a new venture, or building investor-ready market analysis for a startup pitch or business plan.

Sections in SKILL.md

Overview
Core Concepts
The Three-Tier Market Framework
When to Use Each Methodology
Detailed patterns and worked examples

Key facts

Author: wshobson (repo owner); Seth Hobson in the plugin manifest
License: MIT (plugin manifest)
Installs on skills.sh: 11,978 (Nov 2, 2026)
GitHub stars: 42,081 (repo, Nov 2, 2026)
Files: 4 including SKILL.md: 2 reference files and 1 worked example, no scripts
Part of plugin: startup-business-analyst: 5 skills, 1 agent and 3 commands in the repo
Last commit: Oct 30, 2026 (repo)

What it includes

Starts from industry reports and narrows down to your segment.
Best for mature, well-defined markets.
Top-down analysis
Builds from customer segments, counts and pricing.
Best for new or niche markets; SKILL.md calls it the most credible for investors.
Bottom-up analysis
Estimates from the value created and what customers would pay.
Used for new market categories and disruptive ideas.
Value theory
Defines the three tiers with examples and typical SOM share.
The example SOM is 2 to 5 percent of SAM, based on the competitive landscape.
TAM, SAM, SOM framework
Six-step process, industry notes, how to present to investors, and mistakes to avoid.
Steps: define the market, gather data sources, calculate TAM, SAM, SOM, then validate and triangulate.
references/details.md
Where to find market data, free and paid.
Covers research firms, government data, trade associations, company data, search tools and survey tools.
references/data-sources.md
A worked example: AI-powered email marketing for e-commerce.
Bottom-up first, checked with top-down.
examples/saas-market-sizing.md

From the official docs

Questions

What does market-sizing-analysis do?

It makes Claude calculate TAM, SAM and SOM for a startup idea using three methods. It follows a six-step process and can cross-check one method against another.

How do I install market-sizing-analysis?

Use the install box above. On Claude Code the README route is the startup-business-analyst plugin, which also adds 4 other skills, an agent and 3 commands (counted from the repo). The skills CLI command installs only this skill.

Does it fetch market data for me?

SKILL.md names no data service for it to call. A reference file lists places to find data, so the figures depend on what you give Claude or what it finds with the tools you already use. Check any figure before it goes in a pitch.

Does it need an API key?

SKILL.md names none, and the folder bundles no scripts. It holds SKILL.md, 2 reference files and 1 example.

Is it safe to install?

The folder is four markdown files. The plugin route also adds an agent and 3 commands, so use the skills CLI command if you want only the skill.

Which method should I use?

SKILL.md says top-down suits mature markets with industry reports, bottom-up suits new or niche markets and is most credible for investors, and value theory suits new categories.

Information

updated Nov 2, 2026

Repository: wshobson/agents
Folder: plugins/startup-business-analyst/skills/market-sizing-analysis

wshobson/agents skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 9

wshobson/agents README · github.com
marketplace.json · github.com
startup-business-analyst plugin.json · github.com
market-sizing-analysis SKILL.md · github.com
details.md · github.com
data-sources.md · github.com
saas-market-sizing.md · github.com
market-sizing-analysis on skills.sh · skills.sh
wshobson/agents · github.com